I have an old Canon film camera that I'd like take tank pictures with. I'd also like to use it to take tank pictures at the local aquarium (so no tripods allowed).

I am debating between the Canon 50mm and the 100mm macro lens. I know the optics are better with the 100mm, but it seems to me I would have be quite a distance away from the subject if I want to fill the frame with anything but an extreme close-up. I'd also like a lens which I could rest against the glass for stability.

I know normally the longer focal length is better when photographing things like insects, since you can stay farther back and not scare them off, but I would be taking pictures of static objects (sea stars, coral, etc) so that is not a concern for me.

the longer lens will allow you to stay back a bit which will allow for some pictures you might no get if you are too close or at the back of the tank. As well, the 100 will work on full frame size digitals and the 50 won't, or so I am told by a professional who uses Canon. A friend who uses the 50 wishes he had the 100. When I get one for my XSi it will be the 100, which also makes a good portrait lens.

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Join a fish club. Don't have one in your area? Start one.

It depends on how old and what you want to do exactly. For the local aquarium the 50 may be better, for your own tank a 100 would do better. I find public aquariums a rubber lens hood helps, you canget really close to the glass and cut out reflections

I had a 100 mm for my macro, sold it, dumb mistake, lol. It was an awesome lens. I think once you start doing macro you will realize a tripod is a must. Now I use extenders and a canon 500d filter lens for macro, works good, not the same as the dedicated macro lens.

Go with a 100mm. I have the 100m (non L series) and find myself wanting the 180mm and dreaming about the 65mm MP-E (5x) more and more.

A tripod is really a necessity, but you can rest the lens on the glass and get ok pictures. I use a tripod, though, so I can lock up the mirror and avoid blur from the mirror slap.

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-Jonathan

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